Indonesia has some of the world’s richest fishing grounds.
Photograph: Chaideer Mahyuddin/AFP/Getty Images

The number of foreign fishermen stranded on remote eastern Indonesian islands has risen to 4,000.

Many are migrant workers abandoned by their boat captains after the government passed a moratorium on foreign fishing five months ago, the International Organisation for Migration (IOM) said on Friday.

Others have been trapped on the islands for years, after being dumped by fishing boats or escaping into the jungle.

“This is the worst moment in our life right now,” one former slave said. “It is even worse than being in hell. We have to work every day to survive ... There is no hope for us any more.”

Associated Press reported earlier this week that slaves – some of them beaten and locked in cages – are forced to fish, and their catch ends up in the supply chains of American supermarkets and restaurants. IOM said on Friday that the report came after several years of close work with Indonesian authorities to rescue hundreds of fisherman identified as victims of trafficking.

Many of the stranded are men from Burma who went to neighbouring Thailand looking for work. They were taken by boat to Indonesia, which has some of the world’s richest fishing grounds. Others are Cambodian and a few are from the poorer parts of Thailand.

Steve Hamilton, IOM’s deputy chief of mission in Indonesia, said for every man it has rescued, many more need help. With the fishing ban, boats have docked or fled, ditching their crews.

“It is reasonable to expect many are victims of trafficking, if not outright slavery,” he said.

“But for the first time in possibly several years, their feet are touching dry land and there is a real possibility for them to go home, once we and the authorities locate and process them.”

About a quarter of the men are in Benjina, a town that straddles two islands in the Maluku chain, says an Indonesian official who recently visited the area. These men, some abandoned five, 10, even 20 years ago, load and unload fish off boats for food and pocket money, or cut and sell logs in the forest.

One dockworker said: “Our body is here but our mind is at home. If it was possible to walk back home, we would do it right away.”

Another wiped tears as he said, “Our lives have no more value than a dog.”

The moratorium was declared by Indonesia’s new fisheries minister, Susi Pudjiastuti, to determine which ships were not properly licensed and to crack down on illegal foreign boats.

Poaching drains billions of dollars from the country, and Pudjiastuti said on Friday that stamping it out was key to addressing labour abuses. She was horrified knowing fishermen were being enslaved in her country.

“We are not letting this happen,” she said. “In the past, it’s been a normal practice. Not now. I’m not allowing it.”

The Indonesian government has pledged to take legal measures to address what is happening in Benjina and other islands. The Thai prime minister, Prayuth Chan-ocha, said his government was stepping up efforts to prosecute those responsible.

“If they still continue to exploit their fellow human beings, they should not be given any licences to operate businesses in Thailand, and they must receive the punishment they deserve,” he said.

However, earlier this week, Prayuth urged journalists not to report on human trafficking without considering how the news would affect the country’s seafood industry and reputation abroad.

Last year the US State Department blacklisted Thailand for its handling of labour abuses, putting it on par with countries including North Korea and Iran.

The Thai government says it was cleaning up the problem and laid out a plan, including new laws that mandate wages, sick leave and shifts of no more than 14 hours.

On Thursday, Thai politicians voted unanimously to create tougher penalties for violating anti-human trafficking law, including the death penalty.